This invention relates generally to inflator devices such as used in vehicle safety restraint systems and, more particularly, to the provision of pressure relief of gases in such devices under specific circumstances such during bonfire conditions.
It is well known to protect a vehicle occupant by means of safety restraint systems which self-actuate from an undeployed or static state to a deployed state without the need for intervention by the operator, i.e., “passive restraint systems.” Such systems commonly contain or include an inflatable vehicle occupant restraint or element, such as in the form of a cushion or bag, commonly referred to as an “airbag cushion.” In practice, such airbag cushions are typically designed to inflate or expand with gas when the vehicle encounters a sudden deceleration, such as in the event of a collision. Such airbag cushion(s) may desirably deploy into one or more locations within the vehicle between the occupant and certain parts of the vehicle interior, such as the doors, steering wheel, dashboard or the like, to prevent or avoid the occupant from forcibly striking such parts of the vehicle interior.
Inflatable safety restraint installations typically use an inflator device to produce inflation gas for inflating the inflatable airbag in the event of a collision. Many types of inflator devices have been disclosed in the art for inflating an inflatable restraint system airbag cushion. One category of such inflator devices is often referred to as “compressed gas inflators” and generally refers to various inflator devices which contain compressed gas.
As is known, one particular type of compressed gas inflator, commonly referred to as a “stored gas inflator,” simply contains a quantity of a stored compressed gas which is selectively released to inflate an associated airbag cushion.
Another known type of compressed gas inflator is commonly referred to as a “hybrid” inflator. In such an inflator device, inflation gas results from a combination of stored compressed gas and the combustion of a gas generating material, e.g., a pyrotechnic.
One disadvantage of compressed gas inflators is that failure of the inflator pressure vessel can occur during exposure to unanticipated high temperature conditions. In addition to steel, and in order to satisfy light weight specifications, aluminum or an aluminum alloy could be used for the inflator housing. Such materials will not experience problems during normal use, such as during deployment in the event of a collision. However, if the inflator is exposed to a high temperature environment, such as a bonfire, for example, encountered during storage or shipping or in the event of a vehicle fire, the inflator housing structure can degrade tending to rupture or burst. Alternatively, the inflator device can unintentionally discharge causing an uninstalled or unsecured inflator device to be propelled.
Thus, there is a need for an inflator device which provides pressure relief of gases generated during a bonfire, to prevent the inflator from propelling or degrading and rupturing.